Temperature dependence of the ultraweak spontaneous photon emission from soya seeds

Summary The ultraweak radiation emitted from soya seeds during germination has been measured for different values of the temperature (20–35°C). The parameters relative to the photon emission time-counting series have been compared with the ones relative to germination and imbibition; it has been found that the activation energy relative to the process of the photon emission from live seeds is equal to that of the germination process (51 KJ/mole), demonstrating that the two processes are correlated. A function of the experimental parameters which eliminates the explicit dependence of the above biological processes on temperature has been proposed. The authors of this paper have agreed to not receive the proofs for correction.     

Evolution of an 1 MHz ultrasonic cavitation bubble field in a chopped irradiation mode

In this paper the evolution of an ultrasonic cavitation bubble field is studied by means of the void rate, the cavitation noise power and the electric power that feeds the ultrasonic transducer. The ultrasonic irradiation is performed in chopped mode. It is observed two kinds of evolution that differ respectively by a slow (A regime) and a fast (B regime) void rate increase. They correspond to cavitation regimes that are identified as respectively a stable cavitation and an inertial cavitation field. The beginning of the fast increase of the void rate is delayed from the irradiation start and this delay depends on the chopping frequency of the irradiation mode.     

乳化原油的超声波脱水研究

从理论上分析了油中的水滴粒子在超声波辐射下的位移效应,给出了超声波分离油水的理论根据.针对其它物理化学方法不能有效破乳的污水回收油进行了实验,证实了超声波分离乳化原油中油和水的可行性、得到了超声波破乳脱水的声学参数.     

Enhancement of Anammox performances in an ABR at normal temperature by the low-intensity ultrasonic irradiation

A lab-scale ultrasound enhancing Anammox reactor (ABR_U) was established and irradiated once a week by ultrasound with the optimal parameter (frequency of 25.0 kHz, intensity of 1.00 W cm⁻² and exposure time of 36.0 s) obtained by response surface methodology (RSM). ABR_U and the controlled Anammox reactor (ABR_C) without ultrasonic treatment were operated in parallel. The start-up time of Anammox process in ABR_U (59 d) was shorter than that in ABR_C (69 d). At the end of the nitrogen load-enhancing period, NLR (0.500 kg N m⁻³ d⁻¹) and NRR (0.430 kg N m⁻³ d⁻¹) in ABR_U were both higher than NLR (0.400 kg N m⁻³ d⁻¹) and NRR (0.333 kg N m⁻³ d⁻¹) in ABR_C. The results of RTQ-PCR demonstrated that the specific low-intensity ultrasound irradiation improved the enrichment levels of AnAOB in mature sludge. SEM images and the observation of the macroscopic morphology of mature sludge showed that the ultrasound irradiation strengthened the formation of Anammox granular sludge, thereby improved the interception capacity and impact load resistance of the reactor, and enhanced the nitrogen removal performance in ABR_U. The ultrasonic enhanced Anammox reactor based on an ABR with the optimal parameters can promote the rapid start-up and efficient and stable operation of the Anammox process at normal temperature (around 25.0 °C).     

氮分子激光照射增大了LiF:F_3~+心浓度

在液氮温度下采用氮分子激光(337nm)照射已着色的LiF晶体,能有效地产生高浓度的F_3~+心.文中详细地描述了着色LiF晶体中F_3~+心的产生方法、光谱特性及其形成机理.     

Atomic engineering of photon emission with a scanning tunneling microscope

We present measurements of photon emission from individual several-atom silver chains on the NiAl(110) surface, excited by tunneling electrons in a scanning tunneling microscope (STM). The chains were assembled by manipulating single silver atoms on the NiAl(110) surface with the STM. The photon energy of this emission can be tuned by appending a single atom to the chain. These changes in photon emission result from changes in the electronic structure of the silver chain, each electronic state inside the chain being associated with a distinct channel of emission.     

Estimation of temperature elevation generated by ultrasonic irradiation in biological tissues using the thermal wave method

In most previous models,simulation of the temperature generation in tissue is based on the Pennes bio-heat transfer equation,which implies an instantaneous thermal energy deposition in the medium.Due to the long thermal relaxation time τ(20 s-30 s) in biological tissues,the actual temperature elevation during clinical treatments could be different from the value predicted by the Pennes bioheat equation.The thermal wave model of bio-heat transfer(TWMBT) defines a thermal relaxation time to describe the tissue heating from ultrasound exposure.In this paper,COMSOL Multiphysics 3.5a,a finite element method software package,is used to simulate the temperature response in tissues based on Pennes and TWMBT equations.We further discuss different factors in the bio-heat transfer model on the influence of the temperature rising and it is found that the temperature response in tissue under ultrasound exposure is a rising process with a declining rate.The thermal relaxation time inhibits the temperature elevation at the beginning of ultrasonic heating.Besides,thermal relaxation in TWMBT leads to lower temperature estimation than that based on Pennes equation during the same period of time.The blood flow carrying heat dominates most to the decline of temperature rising rate and the influence increases with temperature rising.On the contrary,heat diffusion,which can be described by thermal conductivity,has little effect on the temperature rising.     

Radiative force on atoms from the view of photon emission

In this Letter, we present a possible methodology to directly “read” the force on an atom via the photons emitted from the atom. In this methodology, the mean radiative force on an atom exerted by external fields can be expressed as a function of the average number of emitted photons h N i and its derivatives via the generating function approach developed by us recently.     

Effect of irradiation distance on degradation of phenol using indirect ultrasonic irradiation method

Ultrasound is used as degradation of hazardous organic compounds. In this study, indirect ultrasonic irradiation method was applied to the degradation process of phenol, the model hazardous organic compound, and the effects of irradiation distance on radical generation and ultrasonic power were investigated. The chemical effect estimated by KI oxidation dosimetry and ultrasonic power measured by calorimetry fluctuated for the irradiation distance, and there was a relationship between the period of the fluctuation of ultrasonic effect and the wavelength of ultrasound. The degradation of phenol was considered to progress in the zero-order kinetics, before the decomposition conversion was less than 25%. Therefore, the simple kinetic model on degradation of phenol was proposed, and there was a linear relation in the degradation rate constant of phenol and the ultrasonic power inside the reactor. In addition, the kinetic model proposed in this study was applied to the former study. There was a linear relation in the degradation rate constant of phenol and ultrasonic energy in the range of frequency of 20-30 kHz in spite of the difference of equipment and sample volume. On the other hand, the degradation rate constant in the range of frequency of 200-800 kHz was much larger than that of 20-30 kHz in the same ultrasonic energy, and this behaviour was agreed with the former investigation about the dependence of ultrasonic frequency on chemical effect.     

Enhancement of single‑photon emission from nitrogen‑vacancy centers with TiN/(Al,Sc)N hyperbolic metamaterial

The broadband enhancement of single‑photon emission from nitrogen‐vacancy centers in nanodiamonds coupled to a planar multilayer metamaterial with hyperbolic dispersion is studied experimentally. The metamaterial is fabricated as an epitaxial metal/dielectric superlattice consisting of CMOS‐compatible ceramics: titanium nitride (TiN) and aluminum scandium nitride (Al_xSc_1‐xN). It is demonstrated that employing the metamaterial results in significant enhancement of collected single‑photon emission and reduction of the excited‐state lifetime. Our results could have an impact on future CMOS‐compatible integrated quantum sources.

     

Charged particle emission,photon emission,and plasma formation induced by CO2 laser pulsed irradiation of WC-Co hardmetals in vacuum and in air

The thresholds of charged particle emission, photon emission and plasma formation induced by CO₂ laser pulsed irradiation of WC-Co hardmetals were determined. The influence of the surface roughness and chemical composition on the thresholds and on the mechanism of the plasma formation was considered. The first experimental data were obtained which indicate the possible realization of the emissive mechanism of air optical breakdown in the vicinity of the solid surface.     

Enhancement of oxygen adsorption on silicon following electron irradiation

While electron-stimulated adsorption of oxygen on silicon during electron irradiation is well known, we here report enhanced adsorption of oxygen on both crystalline and hydrogenated amorphous silicon following electron irradiation. The adsorption enhancement is proportional to the energy dissipation at the irradiated surface, and thus is inversely related to the beam energy. Electronic excitation processes are thought to cause bonding changes and thus enhanced adsorption.     

超声辐照及辐照环境对液体中流场分布特性的影响

研究了超声辐照下液体中声压场分布,模拟了流场分布的特性,模拟结果与利用粒子成像测速仪得到的实验结果相符。进一步研究了声学参数及容器几何环境对流场分布的影响。研究发现,增大超声功率和频率可使流场速度变大:在30~60W范围内,超声功率与流场中最大流速间存在线性关系;在频率为100~472kHz范围内,流场速度大小随频率的升高而增加:在层流区,流速与频率的平方成正比;在湍流区,流速与频率的1/2次方成正比。进一步研究发现,随着换能器到容器壁间距离的增加,流场速度减小。     

Effect of ultrasonic irradiation on production of fermented milk with Lactobacillus delbrueckii

Milk fermentation with Lactobacillus delbrueckii under ultrasonic irradiation was carried out in a 450 cm³ bioreactor with a polyethylene film bottom. Ultrasonic irradiation increased the hydrolysis of lactose in milk but decreased the cell viability. However, the viable cell count increased again when the ultrasound was stopped, because ultrasound did not destroy the ability for cell propagation. When the sonication power was 17.2 kW m^-2 and the sonication period was 3 h, 4.9 × 10⁸ cfu cm^-3 of the viable cell count and 55% lactose hydrolysis were attained. In contrast, the viable cell count was 2 × 10⁹ cfu cm^-3 and 35.6% lactose was hydrolysed in control fermentation.     

Enhancement of pulsed laser ablation assisted with continuous wave laser irradiation

Continuous wave(CW) laser irradiation is employed to enhance the pulsed laser ablation of silicon and stainless steel(316 L)samples. Different surface temperatures generated by the CW laser irradiation are set as the initial working circumstance for the pulsed laser ablation. The diameter and depth of laser-ablated craters are measured to study threshold fluence, pulse incubation coefficient and ablation rate under different surface temperatures. Numerical simulation employing Heat Transfer in Solid and Deformed Geometry Interface modules in COMSOL is performed to estimate ablation rate theoretically based on Hertz-Knudsen equation. The realized crater-related data are analyzed to further obtain their dependences on surface temperature. The parametric and morphological studies indicate that the weakened plasma shielding effect and thermal diffusion in the ablated region induced by the CW laser irradiation lead to the enhanced pulsed laser ablation significantly.     

Coincidence studies with polarisation analysis of the photon emission induced inK-inert gas collisions

The linear and circular polarisations of theK(4² P→4² S) transition detected in delayed coincidence with the inelastically scattered potassium atom are presented forK- He, Ne, Ar, Kr and Xe. For all systems the Stokes vector measurements have been performed as a function of the potassium scattering angle at a beam energy of 10³ eV. The coherence properties of the excitation process are studied with the help of the measured degree of polarisation. For He, Ne and Xe the excitation amplitudes (e.g. the parametersλ andχ) are deduced from the measured Stokes vector. For Ar and Kr the collisionally excited state is not a pure state, and it is concluded that both single excitation of theK atom and simultaneous excitation of both collision partners contribute toK(4² P) excitation. The results are compared with the predictions of the semiclassical treatment of the excitation process.     

Enhancement or quenching effect of metallic nanodimer on spontaneous emission

The plasmonic effects of a metallic (Au or Ag) nanodimer on the excitation and emission of a single emitter placed within the gap of the nanodimer are studied to identify its overall performance (enhancement or quenching) for the spontaneous emission. The process of a spontaneous emission is divided into two stages for analysis: the excitation and the subsequent emission stages. For the excitation stage, the amplification of the local electric field around the gap region is studied to show the converging-lens effect of the nanodimer for focusing an incident light. For the emission stage, the apparent quantum yield of an electric dipole (the excited emitter) in the presence of the nanodimer is studied in terms of its radiative and nonradiative decay rates. Both models are simulated by the multiple multi-pole methods for solving Maxwell's equations. The results indicate that the overall enhancement factor of a metallic nanodimer on the spontaneous emission depends not only on its dimension (radius and gap) but also on the absorption and emission spectra of the emitter. Moreover, there is an optimal dimension (radius and gap) of a nanodimer for obtaining the maximum enhancement to a specific spontaneous emission. In addition, the observed emission spectrum of the emitter can be modified by the nearby nanodimer (a low-pass filter), and its lifetime can be reduced by two or three orders of magnitude due to the energy transfer between them.